Apparatus for mixing fluids



May 2 1963 L. E. JOHNSON 3,090,693

APPARATUS FOR MIXING FLUIDS Filed March 1, 1960 2 Sheets-Sheet 1 INVENTOR. Lowell E. Johnson ATTORNEY May 21, 1963 L. E. JOHNSON 3,090,603

APPARATUS FOR MIXING FLUIDS Filed March 1. 1960 2 SheetsSheet 2 FIG. 2

INVENTOR. Lowell E. Johnson ATTORNEY 3,fl%,flfl3 Patented May 21, 1953 flies 3,090,603 APPARATUS FOR MlXHlG FLUmS Lowell E. Johnson, Alliance, (Bhio, assignor to The Babcock dz Wilcox Company, New York, N .Y., a corporation of New Jersey Filed Mar. 1, 1963, Ser. No. 12,014 6 Claims. (Cl. 259-4) This invention relates in general to the construction and operation of apparatus for mixing fluids and more particularly to fluid mixing apparatus especially adapted for use in a forced circulation once-through vapor generating and superheating unit.

Heretofore, the tubular heating surface for the boundary walls of a unit of the character described has been so arranged that the fluid to be heated passes successively through tube panels or sections of each boundary wall. This tube arrangement has given difficulty in that the fluid temperature continuously increases as it flows in series through the boundary walls, with the result that temperature differentials between adjacent tubes, due to unbalanced heat and/or fluid flow distribution, become cumulative along the fluid flow path, thereby creating differential expansions in the Walls of a magnitude which result in high fatigue stresses in the wall-forming compo nents. This problem of undue thermal stress was finally solved by the construction and arrangement of furnace wall tubes disclosed in the co-pending application of Paul H. Koch, Serial No. 685,119, filed September 20, 1957, now Patent No. 3,007,459, wherein the fluid to be heated is supplied in parallel flow relation to the furnace boundary walls and each of the boundary walls is horizontally subdivided into vertically spaced serially connected tubular sections so as to provide interruptions in the fluid flow path at which the fluids discharging from correspondingly located tubular sections of the furnace walls are collected, mixed in the apparatus of the present invention to equalize fluid enthalpies, and then uniformly distributed to the next vertically adjacent tubular sections of the furnace walls.

In accordance with the invention, the mixing apparatus comprises a metallic vessel having a plurality of fluid inlets opening to one portion thereof and each supplied with a stream of fluid having an enthalpy different from the enthalpy of the stream of fluid supplied to the other of the inlets; and at least one fluid outlet opening to another portion of the vessel and longitudinally spaced from the fluid inlets. A V-shaped fluid mixing device is disposed within the vessel and across the flow path of the inlet streams of fluid as they pass from the inlets to the outlet. The mixing device comprises a multiplicity of oppositely arranged laterally spaced plate members defining a multiplicity of fluid flow passages and subdividing each of the inlet streams of fluid into a multiplicity of streams, with opposed plate members being staggered with respect to each other to effect interleaving of the inlet streams so divided and intimate turbulent mixing thereof as they pass to the outlet and thereby provide a substantially uniform enthalpy of the mixed streams upon discharge through the outlet. In the particular adaptation of the apparatus of the invention, equalization of fluid enthalpies at the points of interruption in the fluid flow path in turn promotes uniform fluid flow distribution and the maintenance of temperature differentials between adjacent tubes of the tubular sections of the furnace walls with-in aceptable stress limits.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

Of the drawings:

FIG. 1 is a somewhat diagrammatic illustration of the application of the fluid mixing apparatus of the invention in a forced flow once-through vapor generating and superheating unit;

FIG. 2 is a sectional elevation of the fluid mixing apparatus of FIG. 1 constructed in accordance with my invention.

PEG. 3 is a sectional view taken along the line 33 of FIG. 2; and

FIG. 4 is an enlarged perspective view of a portion of the apparatus of FIG. 2.

The fluid mixing apparatus of the invention is particularly adapted for use at vertically spaced positions along the height and externally of the furnace enclosure walls of a forced flow once-through vapor generator, such as illustrated in FIG. 1 and disclosed in greater detail in the aforesaid co-pending application of Paul H. Koch. It will be understood, however, that he fluid mixing apparatus illustrated and hereinafter described can also be advantageously used in other types of vapor generators and wherever heat and fluid flow distribution conditions render the use of fluid mixing apparatus desirable.

One of the problems in the operation of a forced flow once-through vapor generator is the effect that unbalanced heat distribution to the tubes of furnace enclosure walls can have on fluid flow distribution in the tubes, and, consequently, on tube metal temperatures. When steam or water or mixtures thereof is heated in the parallel flow paths provided by the furnace wall tubes, unbalance in heat distribution can lead to excessive localized tube metal temperatures and/or to excessive temperature differentials between adjacent tubes and, thereby, undue thermal stresses in the furnace wall-forming components.

In order to overcome the problems presented by unbalanced heat and fluid flow distribution, each of the furnace walls of FIG. 1 is horizontally subdivided into a plurality of vertically spaced tubular sections and the fluid to be heated is supplied in parallel flow relation to the lowermost tubular section of each furnace wall, with each tubular section comprising groups of upwardly extending closely spaced parallel tubes. The groups of tubes forming correspondingly located tubular sections in the furnace walls are so connected for series flow of fluid to the tube groups forming the next vertically adjacent tubular sections as to provide, in effect, interruptions in the fluid flow path through the furnace at which the fluids discharging from the parallel flow tube groups of correspondingly located tubular sections of the furnace walls are collected, mixed in apparatus formed in accordance with the invention to neutralize the differences in amount of heat picked up, and then uniformly distributed to the tube groups of the next vertically adjacent tubular sections of the furnace walls. Thus in operation feed water is supplied by a feed pump, not shown, to an economizer 32 wherein it is partially heated. The heated fluid then flows through a downcomer 41 and supply tubes 42 to furnace wall tube supply headers 43, then passes in parallel flow relation through the tube groups forming the lower tubular section of each furnace wall to a continuous horizontal drain and collecting header or conduit 53 disposed externally and about the periphery of the furnace and having two discharge portions arranged to pass the fluids so collected in separate streams to the inlets of a vertically arranged fluid enthalpy equalization or mixing vessel 54 formed in accordance with the'invention and disposed adjacent the juncture of the front and side walls of the furnace. Since it is impossible to obtain perfectly uniform heat and fluid flow distribution, the heat content or enthalpy of the stream of fluid passing to one of the inlets of the vessel 54 will be different from the enthalpy of the stream of fluid passing to the other of the inlets. While the difference in enthalpy may be high, parallel streams of fluid entering the mixing vessel of the invention may have only a small difference in temperature, as would be the case when the fluid is undergoing a change in phase from a saturated liquid to a saturated vapor condition in correspondingly located tubular sections prior to collection for mixing, or may have a large diflerence in temperature, as would be the case when the fluid is being heated from a sub-cooled condition to a saturated liquid condition in correspondingly located tubular sections prior to collection for mixing.

The parallel streams of fluid discharged to the vessel 54 are mixed therein so that the enthalpy, and thereby the temperature, of the resulting mass of fluid will be substantially uniform before passing to the next vertically adjacent tubular sections. After mixing in the header 54, the fluid discharges in separate streams to a combination fluid drain and distribution header 55 of like construction and arrangement as the header 53 for distribution to and flow through the tube groups forming the next vertically adjacent correspondingly located tubular sections of the furnace walls. Flow thereafter is in like order as described. Thus the streams of fluid discharging from tube groups of the next vertically adjacent tubular sections flow to a combination fluid drain and collecting header 56 arranged to pass the collected fluids in separate streams to the inlets of a mixing vessel 54A of the same construction and arrangement as the vessel 54. After mixing in the vessel 54A, the fluid discharges in separate streams to a header 58 for distribution to the tube groups of the following vertically adjacent tubular sections.

As shown in FIGS. 2-4, the fluid mixing apparatus 54 comprises a relatively short substantially cylindrical metallic vessel closed at its opposite ends by walls or heads 12 of hemispherical form. The circumferential Wall of the vessel 10 is formed with pairs of opposed circular inlet and opposed circular outlet openings 14 and 16, respectively, arranged substantially tangentially thereto, with the inlets being longitudinally spaced from the outlets and arranged to introduce streams of fluid into the vessel in opposed angular directions. Each pair of opposed openings have their axes extending normal to each other and'lying in a common plane extending normal to the longitudinal axis of the vessel. Streams of fluid are supplied to the inlets 14 by the discharge conduit portions of the continuous header 53 and are tangentially discharged into the vessel .10 for mixing therein, each conduit portion having its discharge end registering with one of the inlet openings 14 and connected by Welding to the outer surface of the circumferential wall of the vessel 19; While parallel streams of mixed fluid discharge from the vessel 10 through the openings 16 to the pair of inlet conduit portions of the continuous header 55, each of which has its inlet end registering With one of the outlet openings 16 and connected by Welding to the outer surface of the circumferential wall of the vessel.

A V-shaped fluid mixing device 22 is symmetrically disposed within the vessel 10 and across the-flow path of the inlet streams of fluid as they pass from the inlets 14- to the outlets 16. The fluid mixing device 22 comprises a multiplicity of parallel oppositely sloping plate members 24 converging in the direction of the inlets 14 at an included angle of about 90, defining alternately oppositely sloping fluid flow passages 26, and arranged to subdivide each of the inlet streams of fluid into a multiplicity of streams. The two planes in which upstream surfaces of opposed plate members 24 lie intersect in a line normal to longitudinal axis of the vessel near to and upstream of an imaginary plane including the axis of the inlets 14 and extending normal to the axis of the vessel. Opposed plate members 24 are disposed in staggered relation with respect to each other to effect interleaving of the subdivided inlet streams of fluid and intimate turbulent mixing thereof as they pass to the outlets 116 and thereby provide a substantially uniform enthalpy of the mixed streams upon discharge through the outlets 16. Thus equal fluid enthalpies entering the tube groups of the next vertically adjacent correspondingly located tubular sections is assured, thereby promoting uniform fluid flow distribution and the maintenance of tube metal temperatures and of temperature differentials between adjacent tubes within acceptable limits. Each plate member 24 has one end integrally connected to the next adjacent plate member, with the opposite ends of the plate members extending to and formed to match the contour of the inner surface of the circumferential wall of the vessel It and with the opposite end of one or more of the plate members being suitably connected, as by welding, to the inner surface of the circumferential wall. The outermost plate members 24 are L-shaped, while the intermediate or remainder of the plate members are channel-shaped and open in the direction of the outlets 16.

While in accordance with the provisions of the statutes I have illustrated and described herein the best form and mode of operation of the invention now known to me, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by my claims, and that certain features of my invention may sometimes be used to advantage without a corresponding use of other features.

What is claimed is:

1. Apparatus for mixing fluids comprising means forming a vessel having a pair of fluid inlets opening to one portion of said vessel and a fluid outlet opening to another portion of said vessel, means supplying a stream of fluid to each of said inlets for flow through said vessel to said outlet with the stream of fluid supplied to one of said inlets having a unit heat content different from the unit heat content of the stream of fluid supplied to the other of said inlets, and fluid mixing means in said vessel disposed across the flow path of said inlet fluid streams and comprising two adjacent rows of oppositely arranged sloping plate members extending longitudinally of said vessel, the plate members of each row being arranged side'by-side in spaced relation and staggered with respect to the plate members of the other row to form opposed and staggered fluid flow passages.

arranged to sub-divide each of said inlet streams of fluid into a multiplicity of streams and to effect interleaving of the inlet streams so divided and intimate mixing thereof as they pass to said outlet and thereby provide a substantially uniform heat content'of the mixed streams upon discharge through said outlet, with the plate members of each row having their longitudinal axes disposed in a common imaginary plane having the same slope relative to the longitudinal axis of said vessel as the corresponding plate members.

2. Apparatus for mixing fluids comprising means forming a vessel having a pair of fluid inlets opening to one portion of said vessel and a fluid outlet opening to another portion of said vessel, means supplying a stream of fluid to each of said inlets for flow through said vessel to said outlet with the stream of fluid supplied to one of said inlets having a unit heat content different from the unit heat content of the stream of fluid supplied to the other of said inlets, and fluid mixing means in said vessel disposed across the flow path of said inlet fluid streams and comprising two adjacent rows of oppositely arranged alternately oppositely sloping plate members extending longitudinally of said vessel and converging in the direction of said inlets, the plate members of each row being arranged side-by-side in spaced relation and staggered with respect to the piste members of the other row to form opposed and staggered fluid flow passages arranged to sub-divide each of said inlet streams of fluid into a multiplicity of streams and to efiect interleaving of the inlet streams so divided and intimate mixing thereof as they pass to said outlet and thereby provide a substantially uniform heat content of the mixed streams upon discharge through said outlet, with the plate members of each row having their longitudinal axes disposed in a common imaginary plane having the same slope relative to the longitudinal axis of said vessel as the corresponding plate members.

3. Apparatus for mixing vaporizable fluids comprising means forming a vessel having a pair of fluid inlets opening to one portion of said vessel and a fluid outlet opening to another portion of said vessel, means supplying a stream of fluid to each of said inlets for flow through said vessel to said outlet with the stream of fluid supplied to one of said inlets having an enthalpy different from the enthalpy of the stream of fluid supplied to the other of said inlets, and fluid mixing means in said vessel disposed across the flow path of said inlet fluid streams and comprising two adjacent rows of oppositely arranged and alternately oppositely sloping plate members extending longitudinally of said vessel and converging in the direction of said inlets, the plate members of each row being arranged side-by-side in spaced relation and staggered with respect to the plate members of the other row to form opposed and staggered fluid flow passages arranged to sub-divide each of said inlet streams of fluid into a multiplicity of streams and to efiect interleaving of the inlet streams so divided and intimate mixing thereof as they pass to said outlet and thereby provide a substantially uniform enthalpy of the mixed streams upon discharge through said outlet, with the plate members of each row having their longitudinal axes disposed in a common imaginary plane having the same slope relative to the longitudinal axis of said vessel as the corresponding plate members.

4. Apparatus for mixing vaporizable fluids comprising means forming a vessel having a pair of fluid inlets opening to one portion of said vessel and a fluid outlet opening to another portion of said vessel, means supplying a stream of fluid to each of said inlets for flow through said vessel to said outlet with the stream of fluid supplied to one of said inlets having an enthalpy different from the enthalpy of the stream of fluid supplied to the other of said inlets, and fluid mixing means in said vessel disposed across the flow path of said inlet fluid streams and comprising two adjacent rows of oppositely arranged intersecting sloping plate members extending longitudinally of said vessel, the plate members of each row being arranged side-by-side in spaced relation and staggered with respect to and directly connected to the plate members of the other row to form opposed and staggered fluid flow passages arranged to sub-divide each of said inlet streams of fluid into a multiplicity of streams and to eflect interleaving of :the inlet streams so divided and intimate mixing thereof as they pass to said outlet and thereby provide a substantially uniform enthalpy of the mixed streams upon discharge through said outlet, with the plate members of each row having their longitudinal axes disposed in a common imaginary plane having the same slope relative to the longitudinal axis of said vessel as the corresponding plate members.

5. Apparatus for mixing vaporizable fluids comprising means forming a vessel having a pair of fluid inlets opening to one portion of said vessel and a fluid outlet opening to another portion of said vessel, means supplying a stream of fluid to each of said inlets for flow through said vessel to said outlet with the stream of fluid supplied to one of said inlets having an enthalpy different from the enthalpy of the stream of fluid supplied to the other of said inlets, and fluid mixing means in said vessel disposed across the flow path of said inlet fluid streams and comprising two adjacent rows of oppositely arranged intersecting sloping plate members extending longitudinally of said vessel and converging in the direction of said inlets, the plate members of each row being arranged side-by-side in spaced relation and staggered with respect to and directly connected to the plate members of the other row to form opposed and staggered fluid flow passages arranged to sub-divide each of said inlet streams of fluid into a multiplicity of streams and to efiect interleaving of the inlet streams so divided and intimate mixing thereof as they pass to said outlet and thereby provide a substantially uniform enthalpy of the mixed streams upon discharge through said outlet, with the plate members of each row having their longitudinal axes disposed in a common imaginary plane having the same slope relative to the longitudinal axis of said vessel as the corresponding plate members.

6. Apparatus for mixing vaporizable fluids comprising means forming a substantially cylindrical metallic vessel having a pair of opposed circular fluid inlets in the circumferential wall thereof opening tangentially and in opposite angular directions to one pontion of said vessel and a fluid outlet opening to another portion of said vessel and longitudinally spaced from said inlets, means supplying a stream of fluid to each of said inlets for flow through said vessel to said outlet with the stream of fluid supplied to one of said inlets having an enthalpy difierent from the enthalpy of the stream of fluid supplied to the other of said inlets, and fluid mixing means in said vessel disposed across the flow path of said inlet fluid streams and comprising two adjacent rows of oppositely arranged intersecting alternately oppositely sloping plate members extending longitudinally of said vessel and converging in the direction of said inlets, the plate members of each row being arranged side-by-side in spaced relation and staggered with respect to and directly connected to the plate members of the other row to form opposed and staggered fluid flow passages arranged to sub-divide each of said inlet streams of fluid into a mu1- tiplicity of streams and to effect interleaving of the inlet streams so divided and intimate mixing thereof as they pass to said outlet and thereby provide a substantially uniform enthalpy of the mixed streams upon discharge through said outlet, with the plate members of each row having their longitudinal axes disposed in a common imaginary plane having the same slope relative to the longitudinal axis of said vessel as the corresponding plate members.

References Cited in the file of this patent UNITED STATES PATENTS 2,125,913 Goebels Aug. 9, 1938 FOREIGN PATENTS 1,165,927 France June 9, 1958 358,018 Germany Aug. 1, 1920 

1. APPARATUS FOR MIXING FLUIDS COMPRISING MEANS FORMING A VESSEL HAVING A PAIR OF FLUID INLETS OPENING TO ONE PORTION OF SAID VESSEL AND A FLUID OUTLET OPENING TO ANOTHER PORTION OF SAID VESSEL, MEANS SUPPLYING A STREAM OF FLUID TO EACH OF SAID INLETS FOR FLOW THROUGH SAID VESSEL TO SAID OUTLET WITH THE STREAM OF FLUID SUPPLIED TO ONE OF SAID INLETS HAVING A UNIT HEAT CONTENT DIFFERENT FROM THE UNIT HEAT CONTENT OF THE STREAM OF FLUID SUPPLIED TO THE OTHER OF SAID INLETS, AND FLUID MIXING MEANS IN SAID VESSEL DISPOSED ACROSS THE FLOW PATH OF SAID INLET FLUID STREAMS AND COMPRISING TWO ADJACENT ROWS OF OPPOSITELY ARRANGED SLOPING PLATE MEMBERS EXTENDING LONGITUDINALLY OF SAID VESSEL, THE PLATE MEMBERS OF EACH ROW BEING ARRANGED SIDE-BY-SIDE IN SAPCED RELATION AND STAGGERED WITH RESPECT TO THE PLATE MEMBERS OF THE OTHER ROW TO FORM OPPOSED AND STAGGERED FLUID FLOW PASSAGES ARRANGED TO SUB-DIVIDE EACH OF SAID INLET STREAMS OF FLUID INTO A MULTIPLICITY OF STREAMS AND TO EFFECT INTERLEAVING OF THE INLET STREAMS SO DIVIDED AND INTIMATE MIXING THEREOF AS THEY PASS TO SAID OUTLET AND THEREBY PROVIDE A SUBSTANTIALLY UNIFORM HEAT CONTENT OF THE MIXED 